Towards Autonomously-Powered CRFIDs

Batteryless Computational RFID (CRFID) devices present exciting possibilities for ubiquitous computing applications. They require minimal maintenance, are cheap to manufacture, and have small form factors. However, CRFIDs lack autonomy because of the need for constant power from an RFID reader—hindering deployment. In this paper, we propose hybrid power harvesting techniques as a mechanism for designing autonomous CRFIDs. We show that a CRFID equipped with a 11.4 cm2 solar panel can enable autonomous computation, storage, and sensing as well as a two-fold increase in communication range with a reader and a three-fold increase in sensing rate. Energy management challenges specific to CRFIDs include high variability of energy harvesting, workload sensitivities to capacitor size, the difficulty of measuring voltage levels while conserving energy, and risk taking to insure against interrupted computation. We propose simple heuristics to select appropriate capacitor sizes and circuitry to monitor voltage levels on autonomous CRFIDs.